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Abstract

Metaphors are ubiquitous in language and developing methods to identify and deal with metaphors is an open problem in Natural Language Processing (NLP). In this paper we describe results from using a maximum entropy (ME) classifier to identify metaphors. Using the Wall Street Journal (WSJ) corpus, we annotated all the verbal targets associated with a set of frames which includes frames of spatial motion, manipulation, and health. One surprising finding was that over 90% of annotated targets from these frames are used metaphorically, underscoring the importance of processing figurative language. We then used this labeled data and each verbal target’s PropBank annotation to train a maximum entropy classifier to make this literal vs. metaphoric distinction. Using the classifier, we reduce the final error in the test set by 5 % over the verb-specific majority class baseline and 31 % over the corpus-wide majority class baseline. 1

Citations

... a verb is being used literally or metaphorically. Such a system could then activate the necessary metaphoric mappings and initiate the appropriate simulation. 2 Metaphor Work in Cognitive Semantics (=-=Lakoff and Johnson, 1980-=-; Johnson, 1987; Langacker, 1987; Lakoff, 1994) suggests that the structure of abstract actions (such as states, causes, purposes, and means) are characterized cognitively in terms of image schemas wh...

...tion, we used the following method to extract the types of its arguments: 1. Used PropBank to extract the target’s arguments. 2. For each argument, we extracted its head using rules closely based on (=-=Collins, 1999-=-).s3. If the head is a pronoun, use the pronoun type (without coreference resolution) as the type of the argument. 4. If the head is a named entity, use the Identifinder tag as the type of the argumen...

...3. If the head is a pronoun, use the pronoun type (without coreference resolution) as the type of the argument. 4. If the head is a named entity, use the Identifinder tag as the type of the argument (=-=Bikel et al., 1997-=-). 5. If neither, use the name of the head’s WordNet synset as the type of the argument. Consider the sentence The drug is being used primarily to {treat} anemias. The PropBank annotation of this sent...

...system could then activate the necessary metaphoric mappings and initiate the appropriate simulation. 2 Metaphor Work in Cognitive Semantics (Lakoff and Johnson, 1980; Johnson, 1987; Langacker, 1987; =-=Lakoff, 1994-=-) suggests that the structure of abstract actions (such as states, causes, purposes, and means) are characterized cognitively in terms of image schemas which are schematized recurring patterns from th...

...rally or metaphorically. Such a system could then activate the necessary metaphoric mappings and initiate the appropriate simulation. 2 Metaphor Work in Cognitive Semantics (Lakoff and Johnson, 1980; =-=Johnson, 1987-=-; Langacker, 1987; Lakoff, 1994) suggests that the structure of abstract actions (such as states, causes, purposes, and means) are characterized cognitively in terms of image schemas which are schemat...

...system, one of our conventional ways of conceptualizing actions. Conventional metaphors capture generalizations governing polysemy, over inference patterns, and governing novel metaphorical language (=-=Lakoff and Turner, 1989-=-). 2.1 Metaphors vs. Different Word Senses Presumably, one could treat the metaphoric usage of run as a different sense, much in the same way that move forward on a business plan is treated as a diffe...

...orically. Such a system could then activate the necessary metaphoric mappings and initiate the appropriate simulation. 2 Metaphor Work in Cognitive Semantics (Lakoff and Johnson, 1980; Johnson, 1987; =-=Langacker, 1987-=-; Lakoff, 1994) suggests that the structure of abstract actions (such as states, causes, purposes, and means) are characterized cognitively in terms of image schemas which are schematized recurring pa...

...simulation. Such action models provide deep inferential capabilities for embodied domains. They can also, when provided with appropriate metaphoric mappings, be extended to cover metaphoric language (=-=Narayanan, 1997-=-). Exploiting the inferential capabilities of such action models over the broadest domain requires a system to determine whether a verb is being used literally or metaphorically. Such a system could t...

...questions as Which train should I take to get to the airport? requires justifications, predictions and recommendations that can only be produced through inference. One such question answering system (=-=Narayanan and Harabagiu, 2004-=-) takes PropBank/FrameNet annotations as input, uses the PropBank targets to indicate which actions are being described with which arguments and produces an answer using probabilistic models of action...

...to select which arguments to use for features in our classifier. 47 Our approach considers each sentence in isolation. However the distribution of metaphorical usage is not uniform in the WSJ corpus (=-=Martin, 1994-=-),. It is therefore possible that the information about surrounding sentences would be useful in determining whether a usage is metaphorical. CorMet incorporates context in a limited way, computing a ...

...the source and target domains simplifies the representational mechanisms used for inference making it easier to build the world models necessary for knowledge-intensive tasks like question answering (=-=Sinha and Narayanan, 2005-=-). 3 Objective While this work in Cognitive Semantics is suggestive, without a corpus-based analysis, it is hard to accurately estimate the importance of metaphoric information for Natural Language Pr...

...f the head is a pronoun, use the pronoun type (without coreference resolution) as the type of the argument. 4. If the head is a named entity, use the Identifinder tag as the type of the argument (BBN =-=Identifinder, 2004-=-). 5. If neither, use the name of the head’s WordNet synset as the type of the argument. Consider the sentence The drug is being used primarily to {treat} anemias. The PropBank annotation of this sent...